Include instance creation scripts in CPS itself

Description

The two scripts: mkcpsinstance and mkcpsdevinstance aren't in CPS itself because they rely on a priori knowledge of the location of mkzopeinstance.py (note that makecpssite.py is a job for existing Zope instances and that of course both scripts rely on the latter).

They should be included (CPSUtil/bin as usual) by simply make the path to Zope's bin directory an option. Benefits:

will be easier to have more packaging options

they can be called right away on dev boxes with no need of the debian packages.